A raman spectroscopy method of measuring melamine contents in dairy products having different matrixes. The method includes: (a) establishing a database of characteristic curves of dairy products having different matrixes; (b) taking several copies of the dairy products having one certain unknown matrix and adding melamine standard solutions having different concentrations therein, to obtain a series of dairy product samples in which the relative concentrations of the melamine are known; (c) performing raman spectrum testing analysis and obtaining corresponding characteristic peak intensities to obtain a slope of the characteristic curve showing variation of the characteristic peak intensities with the relative concentrations of the melamine; (d) searching the database of step (a) using the slope of the characteristic curve of the dairy product samples to find a matching characteristic curve, and (e) calculating concentration of melamine in the dairy products by using the matched characteristic curve and the characteristic peak intensity.